This invention relates to the field of particulate separation. In particular it relates to the field of air wash separators and related devices utilized for separating particulates, such as abrasives, from sand, refuse and other debris encountered in molding, surface treatment, and like operations. For example, an air wash separator is often employed for separating reuseable abrasives, such as steel shot, grit, or the like, from sand, dust and fines.
An air wash separator, speaking generaly, is a device which passes material to be separated over a lip in a state of essentially, gravity free fall and then blows a curtain of air past the free falling material. The abrasives, being of a higher density than the debris and sand, are deflected less than the debris and sand by the air curtain. Thus, a first receptacle provided directly under the falling stream will receive mostly abrasive particles while the lighter elements will be deflected out of the downward path into a second receptacle provided therefor. The present invention relates to an improvement for air wash separators to deal with the problem of operation during periods when abrasive content is absent from the air wash separator and there is essentially pure sand passing through the device. For a more complete discussion of air wash separators and their applicaion, reference is made to U.S. Pat. No. 3,005,547 incorporated thereby.
In an air wash separator, such as is disclosed in the above referenced U.S. Pat. sand and abrasive to be separated pass over a lip when the quantity of material builds up sufficiently to offset a counter-weighed swinging baffle. The problem solved by the present invention is that due to the weight difference in pure sand from that of a sand abrasive mixture, when pure sand is present the swingable baffle does not operate properly and the air wash separator tends to overflow or back up with sand.
In prior systems for dealing with the sand problem a mechanical trip box system has been utilized to open the swinging baffle during periods when sand surges are passing through the separator. The trip box system was deficient in that it is difficult to properly balance so that the swinging baffle will return to its normal position when the sand surge condition has ended. Further, the trip box was not able to trip far enough to drain or spill out all sand. Thus, it was necessary to add drain holes.
It is accordingly an object of the present invention to provide an improved sensing system for an air wash separator which will open a swinging baffle to permit a sand surge to pass through the device.
It is another object of the present invention to provide a system which will provide a positive and automatic opening of the swinging baffle when a sand surge is present and return the swinging baffle to its normal functioning position after the sand surge has passed.
It is a further object of the present invention to provide a system for handling sand surges in an air wash separator which does not require that the swinging baffle be balanced for sand flow conditions.
It is a further object of the present invention to provide a device which will pass sand surges through the separator in order to remove much of the sand on its first pass through the separator without the need for recycling it to wait for a mixture of abrasives thereby eliminating a need for a bypass system.
Other objects and advantages of the invention will become apparent from the concluding portion of the specification.